A number of electric plugs and electric plug sockets for receiving the plugs is known in the art. These plugs differ primarily in terms of the number, shape, size and arrangement of the contacts, the protection from electromagnetic interference, high-frequency characteristics, and the ampacity. An important feature of electric plugs and plug sockets are fastening or locking devices for the permanent, but generally detachable, fastening or locking of the plug in the plug socket. Whereas the conventional banana plug, the euro mains plug and the plug with earthing contact, for example, are held in the corresponding sockets or outlets merely as a result of the friction of the plug connection, other plugs are held in or on the plug socket using bayonet arrangements, coupling rings or screw flanges.
In the electrical connector industry, latching connections have been found to be particularly advantageous for fastening of an electric plug in or on an electric plug socket. The plug and plug socket are generally connected automatically during insertion of the plug into the plug socket in that latching elements of the plug and plug socket engage with one another. The latching connection may generally easily be released in that one latching element is displaced relative to the other latching element transversely to the insertion direction such that the two latching elements no longer engage. A tensile connection between the plug and plug socket may thus be rapidly made in a particularly simple manner, and subsequently released, via this latching connection. In many cases, a tool is not required even to release the latching connection.
An example of an electric plug that may be fastened in a plug socket by latching is disclosed in WO 02/15340 A1. In that reference, the electric plug comprises a plurality of contacts in a plug contact region on one side. On an opposing side of the plug contact region, a symmetrical pair of latch hooks is arranged on a latch spring. This pair of latch hooks is the only latching element of the plug and may be displaced by pressing an actuating handle in order to release a latching connection.
One drawback of the described conventional plug is that the latching connection of the plug and the plug socket cannot ensure a sufficiently secure connection for industrial use.